The ultimate goal of the proposed studies is to evaluate humoral and cellular immune responses in the mucosal and systemic immune compartments of volunteers immunized with HIV virus-like particles (VLP) vaccines developed in Projects 1 and 2 and Core C, and tested by methods used in Project 3 in monkeys (Core B) To prepare our laboratories for the proposed clinical trial, we wilt optimize humoral and cell-mediated immune detection assays using samples obtained from HIV-1-infected patients. We will especially focus on methods to improve our ability to detect immune responses at mucosal sites. In collaboration with investigators in Projects 1, 2, and Core B, we also propose to evaluate the efficiency of selected mucosal adjuvants (mucoadhesives, bacterial CpG oligonucleotides, poly-L-lysine, and oxidized mannan) to enhance mucosal and systemic immune responses first in animals and later in human participants. The intranasal immunization wilt receive special attention because of the demonstrated efficacy of this immunization route to induce both mucosal and systemic, antibody- as well as cell-mediated immune responses particularly in the genital tract of vaccinated humans and animals. Finally, HIV-1 candidate vaccines designed in Projects 1 and 2, tested in monkeys in Core B, and produced in Core C will be evaluated for their safety and immunogenicity in humans. Our proposed clinical trials will evaluate escalating doses of two candidate HIV VLP vaccines given via intramuscular and or intranasal routes. The presence of HIV-1-binding and neutralizing antibodies of all major isotypes will be determined in sera, at the site of immunization (nasal fluid), in secretions of the male and female genital tract, and in rectal fluid. Cell-mediated immunity will be evaluated in peripheral blood and genital samples with respect to the IFNgamma-secreting CD4+ and CD8+ T cells, and, if present, by CTL activity and tetramer binding. Furthermore, the expression of mucosal and systemic homing receptors will be determined on peripheral blood antibody-secreting B cells and IFNgamma-secreting B cells and IFNgamma-secreting CD4+ and CD8+ T cells of vaccinees immunized by systemic and mucosal routes.